Reply by runswithscissors

Are the bowed parts rails or stiles? In either case, clamp one end in a padded vice (wooden pads will do), with the bowed face towards you. Clamp the other end with a husky C clamp, again using wood pads. Using a heat gun, very carefully heat that face of the piece until it’s very hot, deeply into the wood—but be careful not to scorch it. Using the clamp as a handle, flex the wood toward you, and overbend somewhat, as there will be spring back. Remove the heat, and hold the bend in position until it’s cooled. Should only take a few minutes. This is much more effective than an iron, or any source of heat that only touches the surface. Don’t have a heat gun? HF has a cheap one that will do.

If you overbend too much, you’ll need to apply head again to straighten it out. Oh, there’s no need for any added moisture or humidity at all.

If the heat gets into your glued joints, it may spoil the gluing job, so you may have to redo that.

I do this often. I straightened out a piece of oak crown molding that looked like a ski. I got a good price on it because nobody else wanted it. It has stayed straight ever since.

-- I admit to being an adrenaline junky; fortunately, I'm very easily frightened